Zootaxa 3701 (5): 551–588 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3701.5.3 http://zoobank.org/urn:lsid:zoobank.org:pub:472882BF-6499-47D3-A242-A8D218BE2DFD New species and records of freshwater (Gastrotricha: ) from Sweden

TOBIAS KÅNNEBY Department of Zoology, Swedish Museum of Natural History, Box 50007, SE 104 05 Stockholm, Sweden. E-mail: [email protected]

Table of contents

Abstract ...... 552 Introduction ...... 552 Material and methods ...... 552 Results ...... 555 ...... 557 Order Remane, 1925 [Rao & Clausen, 1970] ...... 557 Suborder d’Hondt, 1971 ...... 557 Family Chaetonotidae Gosse, 1864 (sensu Leasi & Todaro, 2008) ...... 557 Subfamily Chaetonotinae Kisielewski, 1991...... 557 Genus Chaetonotus Ehrenberg, 1830 ...... 557 Subgenus Captochaetus Kisielewski, 1997 ...... 557 Chaetonotus (Captochaetus) arethusae Balsamo & Todaro, 1995 ...... 557 Subgenus Chaetonotus Ehrenberg, 1830...... 557 Chaetonotus (Chaetonotus) benacensis Balsamo & Fregni, 1995 ...... 557 Chaetonotus (Chaetonotus) heterospinosus Balsamo, 1977...... 559 Chaetonotus (Chaetonotus) maximus Ehrenberg, 1838 ...... 560 Chaetonotus (Chaetonotus) microchaetus Preobrajenskaja, 1926 ...... 562 Chaetonotus (Chaetonotus) naiadis Balsamo & Todaro, 1995 ...... 563 Chaetonotus (Chaetonotus) oculifer Kisielewski, 1981 ...... 564 Chaetonotus (Chaetonotus) polyspinosus Greuter, 1917 ...... 565 Chaetonotus (Chaetonotus) similis Zelinka, 1889 ...... 566 Subgenus Hystricochaetonotus Schwank, 1990 ...... 568 Chaetonotus (Hystricochaetonotus) aemilianus Balsamo, 1978 ...... 568 Chaetonotus (Hystricochaetonotus) euhystrix Schwank, 1990...... 569 Chaetonotus (Hystricochaetonotus) hystrix Metschnikoff, 1865 ...... 570 Chaetonotus (Hystricochaetonotus) macrochaetus Zelinka, 1889 ...... 571 Chaetonotus (Hystricochaetonotus) persetosus Zelinka, 1889...... 572 Chaetonotus (Hystricochaetonotus) spinulosus Stokes, 1887 ...... 573 Subgenus Primochaetus Kisielewski, 1997...... 574 Chaetonotus (Primochaetus) acanthodes Stokes, 1887 ...... 574 Chaetonotus (Primochaetus) armatus Kisielewski, 1981...... 575 Chaetonotus (Primochaetus) heideri Brehm, 1917 ...... 576 Chaetonotus (Primochaetus) heteracanthus Remane, 1927...... 578 Chaetonotus (Primochaetus) mutinensis Balsamo, 1977 ...... 579 Chaetonotus (Primochaetus) soberanus Grosso & Drahg, 1983 ...... 580 Chaetonotus (Primochaetus) veronicae n. sp...... 581 Subgenus Zonochaeta Remane, 1927 ...... 584 Chaetonotus (Z.) bisacer Greuter, 1917 ...... 584 Chaetonotus (Z.) succinctus Voigt, 1902...... 584 Discussion ...... 585 Acknowledgements ...... 586 References ...... 586

Accepted by S. Wolfgang: 5 Aug. 2013; published: 22 Aug. 2013 551 Abstract

Chaetonotus is the most speciose genus of the family Chaetonotidae within Gastrotricha, a small phylum of aquatic acoe- lomate invertebrates. The freshwater fauna of Sweden has been studied during the last five years and so far 44 species have been reported in the literature from the country. This study describes the new species, Chaetonotus (Pri- mochaetus) veronicae n. sp., and reports 9 species new to the Swedish fauna raising the known number of freshwater spe- cies from the country to 54. Some records stand out from a biogeographic point of view: Chaetonotus (Primochaetus) soberanus is reported for the first time from Europe and Chaetonotus (Chaetonotus) arethusae, Chaetonotus (Chaetono- tus) naiadis and Chaetonotus (Hystricochaetonotus) euhystrix are reported for the first time outside the countries from which they were originally described.

Key words: Chaetonotida, Freshwater fauna, taxonomy, biodiversity, Meiofauna

Introduction

Gastrotricha are small aquatic acoelomate metazoan , with close to 800 species (see Balsamo et al. 2009; Hummon & Todaro, 2010). In freshwater they are epiphytic or epibenthic and to some extent also interstitial and semi-planktonic. The largest genus is Chaetonotus Ehrenberg, 1830 which includes more than 200 nominal species, is very common, and is taxonomically defined as having scales with spines (Schwank 1990; Balsamo et al. 2009). According to Kisielewski (1997), the genus is divided into 8 subgenera based on the evolution of cuticular scales and spines (but see also Schwank 1990; Weiss 2001; Balsamo et al. 2009): Chaetonotus (Captochaetus) Kisielewski, 1997; C. (Chaetonotus) Ehrenberg, 1830, C. (Hystricochaetonotus) Schwank, 1990; C. (Marinochaetus) Kisielewski, 1997; C. (Primochaetus) Kisielewski, 1997; C. (Schizochaetonotus) Schwank, 1990; C. (Wolterecka) Mola, 1932; and C. (Zonochaeta) Remane, 1927. According to current classification C. (Marinochaetus) is the only subgenus consisting solely of marine species. On the other hand C. (Captochaetus), C. (Primochaetus), C. (Wolterecka) and C. (Zonochaeta) are represented in freshwater environments only, while C. (Chaetonotus), C. (Hystricochaetonotus) and C. (Schizochaetonotus) have representatives in both environments. Chaetonotus has long been known to be a polyphyletic group based on morphological data and most recent based on molecular data (Kånneby et al. 2013). Moreover, also the subgenera C. (Chaetonotus), C. (Hystricochaetonotus), C. (Primochaetus) and C. (Schizochaetonotus) are non-monophyletic groups based on molecular data (Kånneby et al. 2013). A revision of Chaetonotus and its subgenera is highly desirable but a daunting and very time consuming task. Many species suffers from incomplete descriptions and poor delimitation from closely related morphological species, which make a proper identification very hard and sometimes impossible. Additionally, many species have been found on few occasions and/or are restricted to certain geographical areas, which further complicate sampling, re-description and genetic studies. The freshwater gastrotrich fauna of Sweden has been studied during the past five years. To date 44 freshwater species have been reported including five new species that have been described from the country: acidophilum Kånneby et al., 2012; H. joermungandri Kånneby, 2011; H. trapezoidum Kånneby, 2011; skandicum Kånneby et al., 2009; and intermedia Kånneby et al., 2012. The genus Chaetonotus has not been dealt with in any greater detail except for a couple of records presented as associated fauna or used in molecular studies (see Kånneby et al. 2009; 2013). To date 21 freshwater species belonging to Chaetonotus have been reported from Sweden (see Table 1). The purpose of this paper is to present a species new to science and new records of Chaetonotus from Sweden. Moreover, detailed taxonomic accounts are given for most species of Chaetonotus previously only nominally reported from Sweden.

Material and methods

Collection was concentrated in the spring, summer and early fall, took place from August 2007 to July 2010 and included most of the Swedish mainland (Fig. 1). Sampling was conducted with a plankton net with a mesh size of 25 µm or simply by scooping up or squeezing aquatic vegetation, moss and benthic material into a container. Samples were kept in aerated aquaria or in a refrigerator to prevent decomposition. Subsamples were taken from

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